A vertical metal oxide semiconductor field effect transistor (MOSFET), in which a p type (or n type) semiconductor layer is buried in an n type (or p type) semiconductor layer, and which has a super junction structure (hereinafter, also referred to as a SJ structure) having an n type region and a p type region that are alternately arranged, has been used as a power control semiconductor device that has a high breakdown voltage and a low ON resistance. In the SJ structure, the amount of n type impurities which is included in the n type region is equal to the amount of p type impurities which is included in the p type region, whereby an undoped region is simultaneously formed and a high breakdown voltage is achieved. Since impurity concentration of a semiconductor layer is increased by an increase of the breakdown voltage of the semiconductor device, it is possible to achieve an increase in the breakdown voltage and a low ON resistance.
A method for forming the SJ structure includes, for example, a method in which a trench is formed in an n type semiconductor layer, and a p type semiconductor is buried in the trench to form a p type semiconductor layer. However, in this method, a hollow portion (e.g., hole or void) is easily formed inside the p type semiconductor layer.